In signal compression, Huffman coding is widely used to encode an input signal utilizing a variable-length (VL) code table (Huffman table). Huffman coding is more efficient than fixed-length (FL) coding for the input signal which has a statistical distribution that is not uniform.
In Huffman coding, the Huffman table is derived in a particular way based on the estimated probability of occurrence for each possible value of the input signal. During encoding, each input signal value is mapped to a particular variable length code in the Huffman table.
By encoding signal values that are statistically more likely to occur using relatively short VL codes (using relatively few bits), and conversely encoding signal values that are statistically infrequently to occur using relatively long VL codes (using relatively more bits), the total number of bits used to encode the input signal can be reduced.